Automatic train control



Feb. 10,1925. 1,526,290

a. s. BUSHNELL AUTOMATIC TRAIN CONTROL Filed June 9, 1920' l'l IIHh-IH'IIHHI- EUIH 1Q Q 18 1O 6 T 6 III 5 7/ 1%1 OnTrack fiATTORNEY Patented Feb. 10, 1925..

"CHARLES S. BUSHNELL, F RUCHESTIEJH, NEW Willi-till, .hSSllGhl'Ult TU GENERAL lil- WAY SIGNAL CUMPANY, 0f ROCHESTER, NEW YORK, ll. GUEPORUQLTION Uh NEW YO'ItK.

Application filed {lane 9,

7 and circuits by means of which the necessnry controlling impulses or influences may be transmitted from the trackway to moving locomotives, or other railway vehicles, by electromagnetic induction and without mechanical contact.

lln systems of the type to which this invention is more particularly applicable, a voltage or current is induced in a car carried circuit by suitable trackway means, and

this voltage or current is utilized to cause operation of a relay or similar electroresponsivc device so as to set into operation some suitable form of train control mechanism, thereby applying the brakes, regulating the speed or otherwise controlling the movement of the vehicle. The purpose of the present invention is to provide an or ganization of parts and circuits in a sy tem of this type, such that the operation of the relay or similar elect-ro-responsive device. resulting from the voltage or current change in the car carried circuit, will in turn produce a similar voltage or current change, likewise tending to cause operation of the relay, so that the operation of the relay is made more positive and reliable, and-of a longer and more uniform duration.

Uther detail features and advantages of the invention will appear hereinafter as the description progresses.

in describing; the invention in detail reference may be made to the accompanying drawings, in which Figure 1 shows diagrammatically one arrangement of trackway circuits which may be employed in connection with the impulse transmitting means embodying this invention; and

Fig. 2 illustrates in a simplified and diagrammatic manner one form of the car equipment and a track element, the parts being shown more with the view of enawtll]. tierial Illi'o. fid'ffifill.

bling' it easy to understand the principles of the invention than with the idea of showing the construction and arrangement of parts preferably employed in practice.

in the embodiment of the invention illustrated, the transmission of the desired controlling impulses is produced by track elements which are governed in accordance with traffic conditions. Various arrangements of traclrway circuits suitable for this purpose may be employed, and it should be understood that the arrangement shown in Fig. 1 is only typical. Referring to Fig. 1, the track rails l of the railroad track are divided by insulated joints 2 into blocks in the usual way, one block it with the adjacent ends of two other blocks H and J.

being shown. The parts and circuits associated with the various blocks are the same, and for convenience will be given like reference characters, with distinctive exponents. Each of the blocks is provided with a track battery 3 and a track relay 45. the same as in ordinary hlocl: signal systems. lrly invention may he used with or without the usual. fixed signals, depending' upon the type of train control apparatus; and if have illustrated such fixed signals S conventionally, without attempting to illustrate their well lmown control circuits and devices.

'lhe trackway element 1 of my invention in general comprises a magnetic yoke or core and associated coils, and is adapted to influence by electro-magnetic induc tion a cooperating element on a passing vehicle. in the construction illustrated, the trackway clement T comprises a U-shaped core or yoke 5 provided with pole pieces (3, and having coils 7 on its legs which are wound and connected in series so that the electromotive forces generated in these coils by time passing through the yoke 5 are cumulative or additive. These trackway elements 'l are intended totransmit controlling" influences or impulses to a. passing train at one or more control points in each block, in accordance with traflic conditions in the next block in advance alone, or both, the next block in advance and the corresponding block, depending upon the type of train control apparatus employed. In the trackway equipment shown in *ig. 1. a trackway element T is located at the entrance to each block, a short distance in the rear of the insulated joints 2, the normal direction of traffic being from left to right, as indicated by the arrow. The coils 7 of each trackway element T are connected in series in a normally closed circuit in cluding the front contact of a line relay 8. In the arran ement illustrated, the controlling circuit or the line relay 8 includes a front contact of the track relay 4 of the corresponding block and a front contact of the track relay 4 of the next block in advance, so that the coils 7 of the trackway element T at the entrance to each block are in closed circuit under clear traflic conditions, but are open-circuited when either the corresponding block or the nerd block in advance is occupied. The trackway elements T may be located crosswise of the track between the track rails (as shown in Fig. 1), or lengthwise, or outside of either track rail, as preferred.

The car carried element L for cooperating with the trackway elements T comprises a yoke or core 9 having three legs each pro vided with a pole piece 10. 'This oke 9 is supported in any suitable way rom theframe of the locomotive, or other vehicle, and positioned so that two of its legs, which are spaced apart the same distance as the legs of the track element T, willpass directly over the pole pieces ofsaid track element, as shown in Fig. 2. On one of the legs of the-yoke 9, (the middle leg in as; particular arrangement illustrated) is a coil or winding 11, conveniently termed the primary coil; andbn the other two legs are similar coils 12 and 13, conveniently termed secondary coils. The secondary coils 12 and 18 are wound, preferably with the same number of turns, and connected in series so that electr c-motive forces generated therein by flux passing through the legs of the yoke- L in the same direction, either up or down, will oppose each other.

In connection with the system illustrated, there is employed a device of the thermionic or vacuum bulb type, commonly known as audion and conveniently referred to by that term. This audion, being well known in the art, is illustrated conventionally. lllt comprises a filament F, a grid G, and a plate P. This audion is connected up with suitable sources of current illustrated as batteries A, B and C, the primary and secondary coils of the car carried element L, and

a control relay R, so that the operation of said relay R is automatically determined by the controlling condition of the track elements as the vehicie successively passes them. It shouid be understood that these electrical connections take various forms, the arrangement illustrated merely typical.

,The control reiay n may be or any suit- T able type, but I prefer to employ a of weapon a tractive type having its armature balanced about its center of gravity and biased to open by a spring; and in'oonnection with the arran ment of circuits illustrated, I have found it desirable to use a relay having a large number of turns so as to be operable on small currents, and also having a laminated core so as to be quick acting. It will be evident, however, that the structural features of the relay R depend lar ely upon the type of audion employed, an other characteristics of the system. The control relay R is intended to control the. operation of some suitable form of train control apparatus. Since this apparatus forms no part of the present invention, and may take any one of the various forms known in the art, I have illustrated conventionally such a device K in the form of an electro-pneumatic valve, which may be used to vent' the train pipe and apply the brakes directly, or govern the operation of some other form of speed regulating or brake controlling mechanism. This train control device K is normally ener ized, and deenergized when the'control re ay R opens its contacts. In the arrangement of circuits illustrated, the control relay opens its contacts only momentarily, so that if continued operation of the train control device K is desired, some suitable means, such as a stick circuit, should be employed, all in the manner which will be readily understood by those skilled in the art.

The apparatus so far described constitutes the parts of a system which I have selected to' illustrate the principles and'mode of operation of my improvement. In accordance with the present invention, I employ a transformer or induction coil or equivalent device, for inductively coupling the car carried circuit influenced from the trackway, and the circuit controlled by the relay B. This transformer O is shown diagrammatically, and comprises two coils or windings 14 and 15.

The circuit connections between the various devices described will, of course, vary in practice. In the particular. arrangement,

illustrated, the filament F of the auction is heated by the battery A..- The grid G is connected in circuit with the secondary coils 12 and 13 and the battery C, as follows: commencing at the positive terminal of the battery C, wire 16, winding 15 of the transformer Q, wire 1? and the secondary coil 12, wire 18, secondary coil .13 and wire 19 the the grid G, filament F and back to the other terminal of the battery C. The plate P is connected in circuit with the relayil and the batteries E and C, as follows: commencing terminal of the battery B nd 23;, reiay R, wire 22, to the piat- :aiarnent to other terminal of th cry (1; primary coil 11 is normally order to protectthe relay contacts from injury b the arcs accompanying the interruption 0 this inductive circuit, a resistance 32,

is preferably connected in multiple with the relay contacts.

0pcration.Noi-mally the battery C produces a positive potential upon the grid G with respect to the negative end or average potential of the filament F, and thus permits current to flow in the plate circuit through the relay R, on account of the well known characteristic of the audion. The relay R being energized, current flows through the primary .coil 11 and produces magneto-motive force tending to send flux through the yoke 9. When the car is travcling between track elements T, this flux passes in part through the legs of the yoke 9 and in part through leakage paths. The reluctance of the partial magnetic circuit aiforded by the yoke 9 is relatively high. Assume now that the car passes over a track element T which has its coils 7 opencircuited, corresponding to dan rous traf ficconditions ahead. A track e ement T in this condition presents in effect a dead m netic loop for the two lefthand legs of the yoke 9 on the passing car, and it will be evi dent that as the car passes such magnetic loop, the reluctance of the partial magnetic circuit of the yoke 9 through the primary coil 11 and the secondary coil 12 is greatly changed, being decreased from the normal to a minimum and then back to normal as the .car passes the track element. This change in reluctance in turn changes the amount of flux passin through the coils 11-12, the flux norma ly passing througl'i the leakage paths being diverted to the nth of lower reluctance through the iron 0 the yokes 9 and 5. As the flux through the coil 12 is increased, an electro-motive force is induced in said coil which in accordance with well known laws, tends to oppose the current setting up this flux; and the windings are so arranged that this induced electro-motive force opposes the voltage of the battery C and reduces the potential on the rid G The normal potential on the grid if being thus lowered, the current normally flowing in the plate circuit through the control relay R is likewise decreased, and the parts are so proportioned and adjusted that the current through the relay R is reduced in this way below the value of current required to hold its contacts closed. Consequently, the contacts of the relay R open and deenergize the train control device K. As the car again recedes from the track element the flux through the secondary coil 12 again'decreases, but since the train control 7 device has already been actuated the efiect of this decrease of flux need not be considered. Under clear traffic conditions, the coils 7 of the track element T are included in a closed circuit of low resistance; and when the car carried element L passes over a track element in this clear condition, the

car equipment is not influenced, at least sufficiently to cause operation of the relay R.

' This is attributed to the action of the coils 7 which, it is believed, oppose or choke back the passage of flux through the yoke 5 because of the current induced in said coils.

It is found in ractice that the number of turns on the code 7 the length of the magnetic circuits, and the like, may be proportioned so that there is little change in the flux through the secondary coil. 12 as it passes the track element T having its coils in closed circuit. f

It will be evident that track rails or similar masses of iron along the track, will tend to cause operation ofthe control relay R in the same way as a track element T in the danger or stopping condition; and to neutralize this objectionable interference, more particularly in the case of trackrails, the additional 1c and-secondary coil 13 are employed. If th of the outer legs of the yoke 9 ass over a magnetic body, as atrac-k rail, su stantially the same'change in flux takes place through the coils 12 and 13; and since these coils are wound oppositely, the electro-motive forces induced therein are approximately balanced, so that the potential of the grid Gr is not lowered. This feature of the system, whereby it is protected against improper operation by the interference of rails or similarmasses of iron along the track, forms no part of the resent invention, and merely illustrates tlie adaptability of this invention.

The above explanation outlines briefly my understanding of the wayin which the car carried and track elements shown and described cooperate, and act in conjunction with the audion, to cause 0 ration of the control relayRwhen require under dangerous trafiic conditions, and when not required under clear traffic conditions; but other factors not necessary to consider are involved tosome extent in the o eration. This system is disclosed and claimed in other applications.

The transformer or induction coil 0 inductively connecting the rid circuit through the secondary coils 12 811513, and the control circuit through the device K, contacts of. relay R, and the primary coil 11, acts to cause more positive operation of they relay R and prolong the opening of its contacts. When the car passes over a track element danger 51- stopping condition, and the contacts of the relay ll open, in the ma ner already described, the current through winding 14 of the transformer Q is greatly reduced on account of the inclusion of the resistance 32 in the circuit. it is noted here that this resistance 32 optional and may be omitted or replaced by any other means acting to protect the relay contacts. The reduction of current in the winding is, curring when the contacts of the ret y open, acts to induce a voltage in the 15; and these windings 1% and are arranged with respect to the potential or the currents flowing in their respective circuits so that this induced voltage, due to thereduction of current in the winding 14, opposes the battery C and causes a further or continuing decrease in the grid potential, thereby further tending to deenergize the relay R. It is found in practice that the slightest opening of the relay it causes it to open fully and to stay open for a short time, that is, for 3 seconds, or more, dependin upon the proportion and arrangement of the Windings, the normal voltages and the like, Thus, while the reduction in grid potential occasioned by the influence of the track element may be of very short duration, perhaps only suilicient to partly open the contacts of the relay ll, the transformer O acts to increase and prolong the opening of said contacts.

While I have disclosed my invention in connection with a specific type of system enlploying an audion, the invention in its generic aspect contemplates the incorporation of suitable means with a car carried circuit having voltage or current charges induced therein inductively by 'trackway means, and a control circuit responding to such voltage or current changes, such that thecurrent variations in the control circuit resulting from the influence of the traclnvay means upon the car carried circuit will in turn produce the same eiiect upon the car carried circuit. in short, when the current in the control circuit energizing the relay R is reduced, this in turn acts upon the circuit through the secondary coils 12 to produce in this latter circuit the same efiect as the influence of a stopping track element.

I desire to have it understood that the specific embodiment of the invention shown and described is merely illustrative, and does not exhaust the adaptations and modifications of the idea or" means and the functions thereof constituting the invention.

What I claim as new and desire to secure by Letters Patent of the United States is '1. In an automatic train control system of the type in which varia ions of potential are produced in a car carried circuit by electromagnetic induction, the combination normally energized electiosr'e means controlled by said circuit, mining bralre applying means was ap the crests of the train when actuated, 1 an i Means responding to the operation said electroponsive means for producing like var ried circr 2, an au the ty; c specified in claim 1, the combination with the car carried circuit, or" a normally energised relay controlled by said circuit and deenergized when the potential of said circuit i trolled by s to a decrease cuit for carried circuit,

3. lln automatic train control system of the typ specified in claim 1, the combination with the car carried circuit, of a relay deenergized when the potential of said car carried circuit decreases, a control circuit including a front contact of the relay, and means inductively connecting the car carried circuit and the control circuit and arranged to reduce the potential of the car carried circuit when the current in the control circuit decreases.

4, In an an ions of potential in said car carrelay, and means responding current in said another cirsing the potential in the car somatic train control system or the type in which the car carried circuit is influenced temporarily from the trackway by electromagnetic induction under dangerous trafiic conditions, the combination with said circuit, of a relay controlled thereby, a normally closed control circuit including the front contact of said relay, a resistance in multiple with said front contact, and means inductively connecting said control circuit and said car carried circuit.

ln an automatic train control system of the type in which controlling impulses are transmitted from the trackway to mom ing vehicles by electroniagneti and in which the car carried circuit has a counter electro-motive force induced therein under dangerous traliic conditions, a normally energized, control circuit havin P the current therein reduced by the counter eleetro-motive force in said car carried circuit, and means whereby such reduction of current in the control circuit acts automatically to produce a similar counter electro-rnotive force in the car carried circuit.

6. In an automatic train control system, a car carried coil, a circuit and a source of current including said coil, means partly on the track and partly on the car for inducing voltage in said coil opposing that of said source, elwtro-responsive means operated by the decrease in voltage in said circuit, and means controlled'by the electro-responsive means for also producing voltage in said circuit opposing said source.

0 induction rate train control system or" decreases, another circuit con- 7. In an automatic train control system,

car equipment comprising a magnetic core,

a normally energized primary coil and a (ill for varying the reluctance of the magnetic circuit through said core, an audion having its grid connected to said secondary coil, a relay included in the plate circuit of the audion, and means controlled by said relay for producing a change in the potential of said rid. v

8. ar equipment for automatic train control systems comprising a coil and a core therefor adapted to be influenced by electromagnetic induction from the trackway, an audion, a circuit including the coil and con nected to the grid of the audion, a relay in the plate circuit of the audion, a control circuit including the front contact of the relay, and means inductively connecting the control circuit and the first mentioned circuit through the coil, whereby operation of the rela also changes the grid potential and ten s to cause further operation of said relay.

9. Car equipment for automatic train control systems comprising a circuit adapted to be influenced by electro-magnetic induction from the trackway, an audion having its grid potential controlled by said circuit,

' a relay in the plate circuit of the audion,

a normally energized train control device, a control circuit including said device and a front contact of the relay, and means inductively connecting the first mentioned circuit and the control circuit.

10. Car equipment for automatic train control systems comprising a magnetic yoke, primary and secondary coils on the yoke, an audion havingits grid connected to the secondary coil, a relay in the plate circuit of the audion, a train control device, a control circuit including said device, a front contact of the relay and the primary coil, and a transformer having its windings included in the control circuit and the grid circuit. 7

11, Car equipment for automatic train control systems comprising a magnetic yoke having three legs, a normally energized primary coil on one leg, 0 positely wound secondary coils on the ot or legs, .an audion having its grid connected to the secondary coils in series, a relay controlled by the plate circuit of the audion, a normally closed control circuit governed by the relay, and a transformer having its windings included in the grid circuit and control circuit.

12. Car equipment for automatic train control s stems comprising a magnetic yoke having tliree legs, a primary coil on one leg, oppositely Wound secondary coils on the other legs, an 'audion having its grid circuit connected to the secondary coils in series, a

= relay in the plate circuit of the sudden, a

normally energized train control device, and a normally closed control circuit including a source of current and front contact of the relay, the primary coil, and said train control device, and a transformer inductively connecting the grid circuit and the control circuit.

13. In an automatic train control system of the type in which variations in potential are produced in a car-carried circuit, the combination with said circuit, of a normally energized electro-responsive device flue-need in accordance With such potential changes in said circuit,-and automatic means for temporarily extending the time of operation of said device.

14. In an automatic train control system of the type in which variations in potential are produced in a car-carried circuit, the combination with said circuit, of a relay energized and deenergized in accordance with potential changes in said circuit, and automatic means efi'ective upon opening of the contacts of the relay for causing the reenergization of the relay to lag behind the corresponding potential change in said circuit and thereby extend the time of opening of the relay.

15. In a train control system, a relay on a vehicle, means partly on the vehicle and partly on the track for temporarily reducing the current in said relay, and automatic means having limited time of effective action and acting upon opening of the relay contacts to extend the time of such reduction in current through the relay and there by increase the time during which its contacts are opened.

16. In a train control system, a normally energized car-carried circuit, an electroresponsive. device in said circuit. means partly on the car and partly on the track for governing said circuit to temporarily reduce the current through the relay and cause its contacts to open, and automatic means rendered efiective by the opening oi the relay contacts for governin said means to maintain the contacts open or an interval oftime after the trackway control ceases.

17. A train control system comprising a car-carried circuit including a battery, an clectro-responsive device on the car governed by said circuit, means partly on the track and partly on the vehicle for producing in said circuit at times a voltage opposing the battery and thereby cause operation of the electro-responsive device, and automatic means acting automatically upon the operation of the electro-responsive device to temporarily produce additional voltage changes in said circuit and thereby extend the time 'of operation of the electro-responsive device.

18. in a train control system, train control apparatus on a vehicle, electro-responsrve means on the vehicle for governing the the tcackwey ihrough an intecveni gap for changing the current flow se o ll '4 v, e bcansioi-mei ac sive #30 she operation of said device fortemporeriiy producing e potential change in the govei'iiiiig circuit and thereby exeeiid time of operation of said device.

20. Ce? equipment comprising a magnetic core, princely coil and e secondary coii inductively associated with said core, energizing circuieior the primary wii, on eiectro-i'esponsive device, a governing circui't for said device including the sec iidcry coil, and means inductiveiy'conneciiiiig said (Jil'OiiiilS.

21. Car apparatus for rain control systems comp-using, an eieciro-respoiieive device, a cer-cerried ciicui normally seid device, means influenced circuit to cause operation of device, 2, circuit opened'ijy operation of said device, and other car-carried ineens continuaiiy iii ductiveiy connecting said circuits.

22. apparatus 01 fsieiii conci'oi sys tems comprising, an eiecibro-i'espoosive device and governing cii'cuii thereiioc, means influenced iom the breckvvey, and acting upon we increase ii So induce a voii bege in said circuit and cause op of said device, and cfii tic means ecfzing by induction c e ce influenciug said govenii temporarily proio 4" tion of said device 23. Car cc system-s comprising, eiecci' -vesp 0 device, a normally therefor acting c use upon e predecermiccc L KL! rem; in its primary to mined change in poi/anti circuit, and means io in the prime-Ty c, opei'eizion of she eiec 24:. in 2min cont-mi energized ear-carried circu sponsive governed paisily on Jsiie cor end on cine crock i c goemc 1 eusomatic s effective when the eiecti'oresponsive device is operated for rariiy produci iike poieiitiei c129 seid circuit thereby i/emperor long iii o; operation of said 25. locus for tin,

4 J. i 1 531 j mix c0 ieoucc me cuirenu 1110116. me eand inereby cause opening 01' its conscious and eu'comea'uc means rendered effective 3 the ooeniin o: 'ihe relax contacts for tmuiiig the reduction of cucr iiiz 53hr the relay for limited time.

26. Car apparatus for train controi systems, comprising an choice-responsive vice, e car-ca circuit, means inducti. influenced from the treckivey through intei'vening oil for changing the reefs iioW in said circuit and causing opei tion of said device, and automatic mee rendered effective when said device operates 111- i 03 in turn governing the cer-ceiried oi?- cuii; to toioi temporarily the time oi ogofs i device.

- 0 for train control car eiemeoi; lie-vie;

end second i oy cede iiiciudin ieiey acting by iiiducbioii flow o1 cui'reniz 121 seic'i' secon Without mievrupsmg said c 2o. cm epyaiecus 101 ci ceins comprising, a comm-ii tro-resoonsive device of Lee cure pe, a oer-carried circuit from the treck 2,1 for causing o device, a circuit governed by vice, Lind means iuducciveiy ccnnewcii cuics.

epcemcus for train control compi isiiig, coir element ode. W inducciveiv coznmunice-ie Wiilii suitable pareeus along she "treckwey having 3 primary secondary winding there fivo circuits each inciuding one of said Wineiiigs, and eiternecing cumem transformer foiiiiiduccive coupiii'ig circuiis.

mice for brain coii'troi is,

e", a three-legged core 01 a imeffy coil on one of said wound comiecied secdie other iegs, circuii; i1isold p imery cell, i circuit inciud- J: secondary coiis, and separate c inductively cougimg said CilC Q :reus tor ire 1n. cocci: sysccmpi'iswig, "We coils ductively communicate with suitable ap paratus along the trackway, a circuit for each of said coils, an audion associated with one of said circuits, and separate means for inductively coupling said circuits.

32. Car equipment comprising, a car ele ment consisting of a core of ma 'netic material located on the car tomagnetically communicate with an inductive trackwa device, a primary and a secondary coil in uctively associated with said core, an energizing circuit for the primary coil, an electro-responsive device, a governing circuit for said device including said secondary coil, and means for inducing a current in said governing circuit to actuate said electro-responsive device when the current in said energizing circuit decreases.

In testimony whereof I have affixed my signature.

CHARLES S. BUSHNELL. 

